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12-09-2015, 06:54 AM   #1
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Odd K-3 Malfunction: F-- with Recent Lenses

Can anyone help me diagnose this issue? My K-3 has started to misbehave after a short fall. I'm thinking it might have something to do with the lens mount, and might not be K-3 specific, thus I'm posting in the general DSLR forum. Here are the symptoms.
  • If I put a recent lens on, the camera displays "F--" and will only let me shoot wide-open. I can not control the aperture and if I turn off "Using Aperture Ring" in the Custom (C4) menus, the camera won't fire at all. However, AF functions normally, the camera knows the focal length of the lens, and it knows at what F-stop shots are taken! For example, if I put on a Sigma 10-20mm F/4-5.6 and fire off a shot at 10mm and one at 20mm, the EXIF correctly states that the first shot was taken at 10mm and F/4, and the second one at 20mm and F/5.6. Or shooting with a DA70, the EXIF shows 70mm and F/2.4. Or shooting with a Sigma 17-70mm F/2.8-4.5, EXIF shows 17mm F/2.8 and 70mm F/4.5.
  • If I put on an old K 55mm F/2, everything seems normal. I can meter using the green button, and shots are properly exposed. I can see the effects of the aperture ring and the lens is properly stopping down.
  • If I put on a Pentax-A 50mm F/1.7, I can actually control the aperture from the body! However, I can only go down to F/3.5 and no lower.
  • If I put on a Pentax-A 135mm F/2.8, I can't control the aperture from the body at all, and the camera displays F--, just like it does for more recent lenses.
Any clues? Maybe I'm overly optimistic, but I'm wondering if this is something that might be fixable without sending the camera in for a professional repair...

12-09-2015, 07:01 AM   #2
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F__ means usually the camera cannot see the lens. Check all of the contacts on the mount.
12-09-2015, 07:47 AM   #3
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my camera fell with a 300mm f/4.5 attached and it behaved as you mentioned. Try wiggling the lens on the mount to see if the "error" goes away briefly. Notwithstanding, you will likely need to send it in for repair if cleaning the contacts doesn't resolve the issue.

M
12-09-2015, 08:14 AM - 1 Like   #4
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Examine particularly the "Av" contact (third one down). There is no difficulty in taking off the lens mount it's just 5 screws, no complications, and looking underneath. Lay the camera flat on its back and lift it off carefully, keep an eye on the lens locking pin.

12-09-2015, 08:26 AM - 2 Likes   #5
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Yes, it does sound like a lens mount problem. You might be able to repair it yourself.

Your profile lists a K-01. That mount should be identical to the K-3. Compare the mounts side by side to look for differences.

Wiggle the mount relative to the camera body. If it moves then something came loose or broke. Try to gently tighten the screws on the camera mount.

Press down on the data contacts. Do they all move up and down in a similar manner? If one is stuck down see if you can free it.

If you are mechanically inclined and can't see an obvious problem, consider unscrewing the camera mount ring to look beneath it. Be careful before going down this route. Here's some more info on what things look like beneath the metal ring; it's a different camera model but the mount is likely identical: https://www.pentaxforums.com/forums/114-maintenance-repair-articles/306083-k-...nt-repair.html
12-09-2015, 11:14 AM   #6
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Yep, that means the camera does not understand the lens. Dismount the lens, then make sure the lens mount and the camera mount are not damaged, bent, dirty, wet or anything like that. Next, make sure the lens actually gets locked into place when you mount it. So put in the bayonet, then turn it in the correct direction until it clicks into place. Only now are the contacts aligned and the camera even has a chance to read lens info.
it is possible that something got damaged during the fall. If you still have any kind of warranty or trust a repair store, send it in. If you are handy and have the right tools, you can unscrew the camera mount and see if anything is obviously broken, loose. But this can be risky. There are threads about similar procedures being done, so search around a little
12-09-2015, 08:26 PM   #7
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Thanks for all the suggestions folks! Comparing with the K-01, I can see that on the K-3 the metal lens mount ring has come out just a bit in the bottom left quadrant - where the contact pins are. For example, the lens clipping pin (first thing below 9 o'clock) sticks out quite a bit more on the K-01. If I push down on K-3's lens mount ring there or at the bottom, I can see that there is a very slight amount of up/down wiggle in that quadrant. I'll need a smaller screwdriver than anything that I currently have to see if I can simply tighten the nine- and six-o'clock screws or not...

Would it be better to unscrew first to see the state of the screw holes underneath the ring, or should I just directly see if I can tighten the screws to get the ring back down?

(BTW, lenses do still lock in place successfully.)
12-10-2015, 08:08 AM - 1 Like   #8
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Suggest it's worth getting a Moody's Tools JIS #0 screwdriver like this one:

http://www.amazon.co.uk/Moody-Tools-Screwdriver-Type-Pollicis/dp/B004ZQBSOW/...IS+Type+S+%230

Then you'll be pretty set for most little lens issues that involve JIS screws (though for lenses the 00 is better).
If the thread has stripped a bit then you'll probably need eg a bit of epoxy....

12-10-2015, 08:17 AM   #9
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My K-3 had this problem. It's a problem with the contacts on the mount. I tried cleaning mine with (electrical) contact cleaner, and when that didn't help, I had to send it off for warranty service. They cleaned the contacts, and it's been fine ever since.
12-10-2015, 05:21 PM   #10
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Mount or contact problem. I get this problem with FA35 on K100, Sigma 70-300 on K-3 and DA 18-55 on ist DL. Every lens and camera has it hate combination which simply doesn't work. After cleaning and careful mounting they work. All bad combinations have easy mounting in common. They just slide, lock and don't want to work. And switch the body and it works.
12-10-2015, 07:58 PM - 1 Like   #11
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QuoteOriginally posted by Doundounba Quote
Would it be better to unscrew first to see the state of the screw holes underneath the ring, or should I just directly see if I can tighten the screws to get the ring back down?
Seriously doubt tightening the screws will help. Most likely the mount ring is bent slightly. That will need to be fixed. Tightening the screws might work, but you run the risk of stripping them when there is already damage from the fall.

I would try removing the mount and making sure nothing else is broken, then get the mount ring flat (or replace it) and then re-install. Personally I would send it in for service rather than try the repair myself but that's up to you.
12-11-2015, 11:45 AM - 1 Like   #12
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QuoteOriginally posted by jatrax Quote
Tightening the screws might work, but you run the risk of stripping them when there is already damage from the fall.
Yep. If the fall damaged the mount, it probably didn't unscrew the screws. So driving them further in might cause small additional damage without fixing the problem. I agree with the rest of Jatrax' post as well
12-12-2015, 11:36 AM   #13
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QuoteOriginally posted by jatrax Quote
Seriously doubt tightening the screws will help. Most likely the mount ring is bent slightly. That will need to be fixed. Tightening the screws might work, but you run the risk of stripping them when there is already damage from the fall. I would try removing the mount and making sure nothing else is broken, then get the mount ring flat (or replace it) and then re-install. [...]
Good advice. Since it seems that I'm unlikely to break anything further by removing the mount ring, that's exactly what I'll try (once I have a screwdriver). If straightening the ring doesn't fix it, *then* I'll send it in... I'll update the thread after the attempt. Thanks again!

Last edited by Doundounba; 12-12-2015 at 11:53 AM.
12-30-2015, 11:41 AM   #14
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Woohoo!

Sooo... I got the screwdriver and removed the ring. Looked at each screw hole and could see no damage; tested each screw without the ring to see if it still screwed in properly, and every one did. Examined the ring itself closely on a flat surface, and it seemed flat. Put it back in, and put the screws back in. I was careful not to over-tighten them. Indoor testing with various lenses and... everything seems to work perfectly!

Thanks to everyone for their help. $10 for a screwdriver instead of a $200+ repair visit equals a much appreciated saving in the holiday period!

Last edited by Doundounba; 12-30-2015 at 11:55 AM.
12-30-2015, 02:29 PM   #15
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Learning mechanics - priceless. So something had moved a bit and light treatment helped to get them back to right places.
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